The etched wafers have been coming out with a brown dusty haze over most of the area. This is for a recipe where the main step is the standard DEEP step using SF6 and C4F8. This was noticed on a wafer run last night and I understand that the same result was seen on a 2nd wafer run today. All process parameters read OK during process. Is there an idea of what the root-cause might be and how we fix it. Btw, we have run several wafers with the same recipe in the last few days with good results